Evite DIY Bat & Ghost Garlands --- It says to spray paint the styrofoam balls, but I've known styrofoam to melt a little from whatever the chemical propellant is spray paint, so don't expect the bats to be perfect.
15 Amazing DIYs for Halloween Decor: 5. Flying Bats
DIY: You can make a Haunted Mansion Halloween Party invitation from any logo found online. All you need is photoshop, a printer, heavy paper stock and perhaps the Ravenscroft font.found on this pin board.
Candy Filled Balloon Pumpkins - Halloween Party Favors